A lithographic apparatus is a machine that applies a desired pattern onto a substrate, usually onto a target portion of the substrate. A lithographic apparatus can be used, for example, in the manufacture of integrated circuits (ICs). In that instance, a patterning device, which is alternatively referred to as a mask or a reticle, may be used to generate a circuit pattern to be formed on an individual layer of the IC. This pattern can be transferred onto a target portion (e.g. comprising part of, one, or several dies) on a substrate (e.g. a silicon wafer). Transfer of the pattern is typically via imaging onto a layer of radiation-sensitive material (resist) provided on the substrate. In general, a single substrate will contain a network of adjacent target portions that are successively patterned. Known lithographic apparatus include so-called steppers, in which each target portion is irradiated by exposing an entire pattern onto the target portion at one time, and so-called scanners, in which each target portion is irradiated by scanning the pattern through a radiation beam in a given direction (the “scanning”-direction) while synchronously scanning the substrate parallel or anti-parallel to this direction. It is also possible to transfer the pattern from the patterning device to the substrate by imprinting the pattern onto the substrate.
In a chip production facility, or a substrate processing facility, a lithographic apparatus is usually directly connected to a track module. At least one of the processing steps performed by the track module, i.e. the post-exposure bake step, can be time critical. Variation in time between the exposure and the bake of a substrate may then result in variations in obtainable critical dimension (CD). Furthermore, the reliability of the (single) track module or scanner module partly determines the reliability of the entire substrate processing facility (when a module is down, the entire production line is typically down). A track module is in general controlled using a fixed frequency, whereas a lithographic apparatus is more event driven (one exposure step possibly takes much longer than another exposure step for the same substrate).
An inline cluster of a track module and a lithographic apparatus may be created, which eliminates two intermediate transport steps between the track module and the lithographic apparatus. Such a cluster can process substrate layers that require a single or two (or more) consecutive lithographic exposure steps (“double exposure”). A potential problem of such a cluster is that the performance of this linked cluster may be determined by the slowest component in the cluster. The handling complexity in the track module that combines both the coat (i.e., substrate input path) as well as the post exposure bake (PEB) and develop (i.e., substrate output path) processes can result in a situation where the slowest of these steps determines the throughput of the other steps. Therefore, as a result of speed differences and different control strategies, the combination of track module and lithographic apparatus may not always be used at maximum efficiency.